Sub‑ion‑scale energy‑conversion pathways in magnetosheath turbulence

Turbulent small‑scale dynamo action, magnetic reconnection, and kinetic instabilities in fully three‑dimensional magnetosheath turbulence must be investigated together to understand how energy is exchanged, redistributed, and dissipated in a collisionless plasma. Clarifying how these processes coexist and how they may sequence in time is essential for understanding turbulent energy transfer at sub‑ion scales. Using high‑resolution tetrahedral MMS observations in the magnetosheath, we compute a suite of diagnostics that characterize the dynamical role of velocity‑gradient structures, including field‑aligned stretching of the magnetic field, compressive motions, pressure–strain interactions, field–particle energy conversions, and pressure‑anisotropy instability measures. All quantities are derived directly from MMS time series. The measurements errors in the considered quantities are evaluated through Monte‑Carlo–based uncertainty analysis. As a working hypothesis, we examine whether regions with strong field‑aligned stretching or compression tend to coincide with magnetic‑field amplification associated with pressure‑anisotropy instabilities, conditions that may be favorable for turbulent dynamo‑like behavior. Conversely, we test whether intervals containing potentially reconnecting thin current sheets exhibit enhanced current density, elevated field particle and pressure-strain interactions and anisotropy relaxation. To explore the temporal relationships between these processes, we apply cross‑correlation analysis to the above diagnostic measures. This approach allows us to assess whether dynamo‑like amplification statistically precedes current‑sheet formation and dissipation, or whether these processes tend to overlap. Early results suggest that both ordered sequences and simultaneous occurrences are possible, reflecting the intermittent and multi‑scale nature of collisionless turbulence. The combined diagnostic and uncertainty‑quantification framework offers a possibility to evaluate the occurrence rates of magnetic‑field amplification, reconnection, and dissipation processes in collisionless space plasmas.